Le Crouesty's port is equipped with a RONIM tide-gauge since january 2002. The observatory is managed by the SHOM in partnership with Météo France and the Joint Associationof Ports andnauticalBasesof Morbihan.

Situated in the far Western corner of the harbourmaster’s in the portof Le Crouesty, the observatory was equipped on 11 February 2002, with a Krohne BM70 sensor, which was replaced on 2 June 2009by an Optiflex radar telemeter.